"Gadolinium is unique for its high magnetic moment and for its special Curie temperature (above which ferromagnetism vanishes) lying just a room temperature, meaning it could be used as a magnetic component that can sense hot or cold."

~300 K

The Curie temperature is the point at which certain metals loses the behavior of ferromagnetism, when metals stay magnified after being exposed to a magnetic field. This phenomenon, called hysteresis, occurs at the atomic level where unpaired electrons spin to line up parallel in an area called the domain. Although the magnetic force within a domain is strong, without an external magnetic force to line up the domains, the metal as a whole does not exhibit magnetism. When domains line up with each other as a result of a magnetic field, the metal is magnetized. Iron, nickel, cobalt and gadolinium, dysprosium and some other rare metals show this behavior.

Unlike the other more common ferromagnetic metals, which have a curie temperature of well over five hundred Kelvin, Gadolinium's Curie temperature is around room temperature at 293 Kelvin. Besides being superconductivity at extremely low temperatures and is strongly magnetic at room temperature, Gadolinium is the only metal outside the fourth period metals that shows signs of ferromagnetic properties. Today Gadolinium alloys are used in televisions, MRI, and in microwaves but in the future its ferromagnetic properties can be used to detect cold or hot environments.